Anthocyanin accumulation and changes in activities of phenylalanine ammonia-lyase and chalcone synthase in roselle (Hibiscus sabdariffa L.) callus cultures.

Time-course changes in anthocyanin accumulation, phenylalanine ammonia-lyase activity and chalcone synthase activity were examined in roselle callus tissues incubated under different culture conditions. Phenylalanine ammonia-lyase activity was not affected by either the kind of auxin supplemented to the medium or light regime. In contrast, chalcone synthase activity was markedly suppressed when the callus was cultured with a medium containing indole-3-acetic acid instead of 2,4-dichlorophenoxyacetic acid (2,4-D) or in the dark. The results imply that in roselle callus cultures chalcone synthase plays a more important role in anthocyanin biosynthesis regulated by 2,4-D and light irradiation than phenylalanine ammonialyase.